Temperature compensating comparator

Abstract

An emitter-coupled differential comparator compares a horizontal rate ramp signal with a vertical-frequency parabola in a television context for producing horizontal rate pulses duration-modulated at the vertical rate. The comparator is arranged to compensate for a temperature-dependent differential-mode component of the signal sources. The compensation is provided by a temperature-responsive element coupled in the emitter circuit of one of the emitter coupled transistors.

What is claimed is: 
     
       1. An emitter coupled differential comparator arrangement in which changes in the switching point of said comparator result from a temperature-responsive differential-mode component between the sources being compared, comprising: first and second transistors;   a current source;   means coupling said current source to the emitters of said first and second transistors by first and second current paths;   energization and utilization means coupled to the collector electrodes of said first and second transistors;   first and second voltage sources coupled to the bases of said first and second transistors, said first voltage source having a temperature-responsive differential-mode component relative to said second whereby said changes in said switching point result; and   temperature-responsive conductive means coupled in said first current path for offsetting said differential comparator as a function of temperature to compensate for said temperature-responsive component between said sources for producing a component poled to reduce said temperature-dependent change in the switching point.   
     
     
       2. An emitter coupled differential comparator according to claim 1 further comprising second conductive means coupled in said second current path, said second conductive means having a temperature characteristic substantially less than that of said temperature-responsive conductive means for offsetting the component of said temperature-responsive conductive means at a particular temperature. 
     
     
       3. An emitter coupled differential comparator according to claim 2 wherein said component is a voltage. 
     
     
       4. An emitter coupled differential comparator according to claim 1 wherein said component is a voltage. 
     
     
       5. An emitter coupled differential comparator according to claim 4 wherein said temperature-responsive conductive means comprises a semiconductor diode. 
     
     
       6. An emitter coupled differential comparator according to claim 4 wherein said temperature-responsive conductive means comprises a semiconductor junction. 
     
     
       7. An emitter coupled differential comparator according to claim 6 further comprising second conductive means coupled in said second current path, said second conductive means having a temperature characteristic substantially less than that of said semiconductor junction for offsetting the voltage of said diode at a particular temperature. 
     
     
       8. An emitter coupled differential comparator according to claim 7 further comprising third conductive means having a temperature characteristic substantially less than that of said semiconductor junction coupled in said first current path for controlling the gain of said comparator. 
     
     
       9. An emitter coupled differential comparator in accordance with claim 8 wherein said semiconductor junction is a diode. 
     
     
       10. A comparator which compensates for relative differential-mode components of signal sources being compared, comprising: first transistor means including a collector electrode and also including a base electrode coupled to a first signal source;   second transistor means including a collector electrode and also including a base electrode coupled to a second signal source having a temperature-responsive differential-mode component relative to said first signal source;   temperature-responsive conductive means including a first and second electrode and having a temperature characteristic substantially equal to the differential-mode component of said first and second signal source;   temperature-stable conductive means including first and second electrodes and having a temperature characteristic substantially less than that of said temperature-responsive conductive means;   first coupling means for coupling said first electrodes of said temperature-responsive and temperature-stable conductive means together at a junction;   a current source coupled to said juncture;   energizing and utilization means coupled to said collectors of said first and second transistor means; and   second coupling means for coupling each of said second electrodes of said temperature-responsive and temperature-stable conductive means to respective emitter electrodes of said first and second transistor means in such a manner that said differential-mode component of said signal sources is compensated.   
     
     
       11. A temperature compensating comparator for use in conjunction with signal sources having a relative temperature-dependent differential-mode variation, comprising: first transistor means including a base electrode coupled to a first signal source and further including emitter and collector electrodes;   second transistor means including a base electrode coupled to a second signal source having a temperature dependent differential-mode variation relative to said first signal source, and further including emitter and collector electrodes;   temperature-responsive conductive means having a temperature response characteristic substantially equal to the relative variation between said first and second signal sources;   temperature-stable conductive means having a temperature response substantially less than that of said temperature-responsive means;   a current source;   first coupling means for coupling said temperature-responsive and temperature-stable conducting means in parallel as to said current source and for providing currents at an electrode of said temperature-responsive conductive means and at an electrode of said temperature-stable means;   second coupling means for coupling said electrode of said temperature-responsive conductive means to said emitter of said first transistor means;   third coupling means for coupling said electrode of said temperature-stable conductive means to said emitter of said second transistor means; and   utilization and supply means coupled to said collector electrodes of said first and second transistor means.